A steel cord for reinforcing rubber articles used for a tire or the like is manufactured by twisting a plurality of steel filaments together by a twisting machine. Examples of the steel cord twisting machine include a tubular type twisting machine and buncher type twisting machine; when a steel cord is manufactured, an exchange operation of a steel filament which is a material is indispensable. Therefore, an operation of knotting a steel filament left on the twisting machine and a newly exchanged steel filament which is a material is performed.
In recent years, for the simplicity of the structure of a steel cord or an increased tenacity of a steel cord, a steel filament having a large diameter is increasingly used. Accordingly, in an operation of knotting steel filaments together which has conventionally been performed manually, an operation load is increasing due to the increase in the flexural rigidity as the result of increased diameter of a filament. Further, since the diameter of the knot of steel filaments tends to be large, room for the diameter of a guide hole through which a steel filament of a twisting machine passes becomes insufficient, whereby the knot is hard to pass through the hole, which has been problematic.
As a connecting device of a metal filament body such as a steel filament, Patent Document 1 discloses a method in which
A pair of spur gears on which slits and through holes which can hold a metal filament body are provided at an interval are arranged at an interval,
the neighborhoods of the ends of metal filament bodies are held at the through holes and slits of these spur gears and the metal filament bodies are bridged such that the neighborhoods of the ends of metal filament bodies are overlapped along the axis direction, and
the spur gears are revolved centering on a point between the through hole and the slit as a center of rotation in directions which are opposite to each other, whereby the metal filament bodies are twisted together between these spur gears while restricting the movement outside a spacer in a diameter direction and connected with each other.
Patent Document 2 discloses a connecting device for mechanically connecting the ends of two thin wire rods, the connecting device comprising two legs rotatably connected to each other centering on a common axis, and a fixed wire rod holding member, each of the legs being configured as a grip at one end thereof, and one of the legs having a toothed segment on the other end thereof, and the other one of the legs being configured integrally with a casing at the opposite end, the toothed segment cooperating with a gear having a slit reaching the axis in the casing, and a fixed wire rod holding member(s) being arranged on one side or on both sides of the gear having a slit.
This device functions as a wire rod clamping device in which a gear having a slit can rotate, is connected with a toothed segment via a transmission device such that the device can be driven by the transmission device, and has on one side a cylinder piece which has a similar slit and is coaxially arranged, the cylinder piece having an automatically operated clamping device. While a fixed wire rod holding member is configured as a wire rod guide not having a clamping action, an unrotatable clamping device which can be operated by using a cam disk of a gear having a slit attached to a lever having a toothed segment on the opposite side to a cylinder piece having a slit spacing from the gear by a predetermined distance and which can be operated via a push rod or a ball involving a buffer action by a spring is arranged. Further, Patent Document 3 discloses a tool for twisting wires by providing rotation at a portion where two wires are held to connect the two wires.